The present invention relates generally to outrigger beam structures. More particularly, it concerns an extension beam which is connected to an outer end of an outrigger beam, with the extension beam being selectively pivotable, around a vertical axis, about the outrigger beam from a working position to a non-working or storage position.
Retractable and extensible outrigger assemblies are usable, for example, on certain utility vehicles for the maintenance of stability of the vehicle and prevention of tipping while the vehicle is performing a work function. Such vehicles notably include truck cranes which have to be sufficiently narrow to safely traverse a highway en route to a worksite but need an enlarged pedestal of stability when working at the work site. Usually, two outrigger assemblies are provided on the vehicle, one located rearwardly of the crane and another one forwardly of the crane. Each outrigger assembly normally has one outrigger beam extendable substantially outwardly from each side of the vehicle. A float assembly is located at an outer end of an outermost outrigger beam and has a vertically extendable and retractable plate-like foot for engagement with the ground or other support surface. Vertical extension and retraction of these plate-like feet, commonly known as pads or float pads, is generally accomplished by a jack cylinder.
Difficulties have, however, been encountered with conventional construction vehicles having a single stage outrigger beam because the outrigger spread provided by the single stage outrigger beam is not adequate to stabilize the construction vehicle under some circumstances. For example, with a larger outrigger spread, a mobile crane is allowed to have either a greater lift capacity at the same boom length or the same lift capacity at a longer boom length without, in either case, a decrease in stability for the crane. It is evident that the length of a single stage outrigger beam is limited by the width of the vehicle into which the beam is retractable. Naturally, multi-stage hydraulically extensible outrigger beam assemblies could be used, however, such assemblies are much more expensive, and more complex mechanically, than a single stage outrigger beam assembly would be.
Various arrangements have been disclosed to increase the outrigger spread of a construction vehicle without resorting to multi-stage outrigger structures. When, instead of a multi-stage outrigger beam, an extension beam is secured to the end of a single stage outrigger beam, a longer outrigger spread is afforded without having to resort to a two stage outrigger beam with its accompanying piston and cylinder complications as well as much greater cost and complexity. Such a system would have a lighter weight than a multi-stage outrigger system thereby improving the fuel economy of the vehicle. Alternatively, with the use of a longer outrigger spread, a lighter counterweight could be used thus also decreasing the weight of the vehicle thereby improving its fuel economy and lessening the wear and tear on both the vehicle and the road surface which is traversed by the vehicle.
A road vehicle derrick having two extension beams pivotally mounted to a main beam, about a horizontal axis, is known to the prior art. Secured to each end of the main beam are a pair of hinge members and an associated end of each extension beam is provided with an upper lug and a lower lug with the lugs fitting between the sides of the hinge members. Passing through each hinge member and a respective upper lug is a bolt with a removable pin being employed to connect the lower end of each hinge member to a respective lower lug. When the extension beams are not in use, the pins may be withdrawn and the extension beams pivoted upwardly about the bolts onto a decking of the vehicle. Vertically adjustable supports which help stabilize the construction vehicle are located at outer ends of each of the extension beams. Such a known outrigger structure is disclosed in U.S. Pat. No. 2,519,910 issued to Kershaw. It would be desirable, however, to provide an outrigger extension which is mounted for pivotal movement around a vertical axis since an extension pivotable around a horizontal axis is unsuitable in a large assembly because it is too heavy to manipulate manually. Also, it would be desirable to provide an extension beam which can be secured in a storage position by a locking bar or bracing member.
A truck-mounted scaffold having an outrigger assembly with a pair of telescoping stabilizer bars is also known to the prior art. Each stabilizer bar is provided with a jack post at an outer end thereof with the jack posts being pivotable about a horizontal axis from a stored position to an erect position for use. To retain the jack posts in a folded storage position, a hook is provided. The hook is welded to a flange on each jack position with the hook engaging a loop fixed to one end of each of the channel members. Such an outrigger structure is disclosed by U.S. Pat. No. 3,825,095 issued to Clark. It would be desirable, however, to have an outrigger beam assembly having an extension beam which is pivotable around a vertical axis, for ease of manual handling as explained above, and which can be secured in a storage position by a bracing member or locking bar.
An excavator having a plurality of folding support legs which are mounted for rotation, of somewhat more than 90.degree., about a vertical axis is also known to the prior art. Such an excavator is disclosed in U.S. Pat. No. 3,987,563 issued Baur. It would be desirable, however, to have a hydraulically extensible outrigger beam to the end of which is pivotally connected an extension beam which may be secured in a storage position by a locking bar.
To extend the outrigger spread of a larger construction vehicle, an extension beam which is pivotable about a vertical axis around an outrigger beam from a storage position to a working position is preferred because manual pivoting of an extension beam around a horizontal axis is not feasible due to the weight of the extension beam. Two examples of outrigger assemblies pivoting around a horizontal axis, but hydraulically powered nevertheless, in lightweight vehicles such as backhoes are disclosed in U.S. Pat. Nos. 4,236,643 and 4,256,433. Conventional jack cylinder and pad assemblies for vehicle outrigger beams are disclosed in U.S. Pat. Nos. 3,990,714 and 4,071,147.
Accordingly, an outrigger beam assembly according to the present invention includes at least one single stage outrigger beam and an extension beam which is pivotally connected to an outer end of the outrigger beam. Securing the extension beam to the outrigger beam are at least two selectively removable pins, each pin passing through cooperating hinge portions on the extension beam and the outrigger beam. When at least one of the pins is removed, the extension beam may be pivoted around a hinge line, which is a vertical axis passing through the remaining pin or vertically aligned pins, to move the extension beam from a working position to a non-working or storage position. A locking bar may be used to secure the extension beam in the storage position such that one end of the locking bar is pinned to a hinge portion on the extension beam and the other end of the locking bar is pinned to a hinge portion on the outrigger beam. In this way, hinge portions which would be pinned together if the extension beam were in a working position are spaced apart. Alternatively a pair of apertures may be provided on the hinge portions such that the apertures become aligned when the extension beam is rotated to the storage position. A pin is inserted through the aligned apertures to secure the extension beam in the storage position.